1. Field of the Invention
The present invention relates generally to a disk drive apparatus for driving a disk cartridge, such as a so-called micro-floppy disk cartridge, which has a sliding shutter for opening and closing a disk access opening. More specifically, the invention relates to a disk drive apparatus which has a cartridge holder having a cartridge insertion mouth for accepting and ejecting the disk cartridge.
2. Description of the Background Art
As is well known, a disk drive apparatus generally comprises a chassis with a turn table, a cartridge holder which is movable forward and aft in the chassis, and a shutter operating pin for opening and closing a sliding shutter of a disk cartridge. When the disk cartridge is inserted into the cartridge holder for loading, the shutter operating pin enters or engages with an operating pin receptacle formed in the shutter for causing sliding movement of the shutter for opening.
The shutter operating pin is carried by a shutter operating arm which is pivotable in both the shutter opening direction and the shutter closing direction. The shutter operating arm is biased toward an initial position, i.e. the shutter closing direction, by means of a return spring. When the disk cartridge is first inserted into the cartridge holder, the shutter operating pin engages with the operating pin receptacle. Upon further insertion of the disk cartridge, the shutter operating pin is axially displaced. The axial movement of the shutter operating pin causes pivotal movement of the shutter operating arm so as to cause lateral or transverse displacement of the shutter operating pin carrying the shutter. Therefore, when the disk cartridge is fully inserted, the shutter is placed at the fully opened position for permitting access to the disk. One example of the aforementioned type of conventional disk drive apparatus has been disclosed in Japanese Patent First (unexamined) Publication (Tokkai) Heisei 1-143064.
Such construction of the conventional disk loading mechanism of the disk drive apparatus is advantageous for simple manufacture and for allowing disk loading without requiring any drive power source. Furthermore, since the aforementioned construction is mechanically associated with the shutter operating mechanism, it may ensure automatic shutter opening operation. On the other hand, the return spring may constantly exert a spring force on the disk cartridge in order to resiliently place the disk cartridge to the eject position upon unloading. This creates difficulty in accurately chucking the disk in the disk drive mechanism.
In particular, the spring force of the return spring affects the disk loading mechanism, including the motor driven disk lifting mechanism for lifting the cartridge holder up and down between the disk loading and unloading positions. Namely, when the cartridge holder with disk cartridge inserted moves from the unloading position to the lowered loading position, the motion of the disk cartridge cannot be restricted until the positioning pin engages the disk cartridge. As a result, the disk cartridge can be pushed backward to project from the disk cartridge receptacle mouth of the cartridge holder.
In order to solve this problem, there has been proposed an arm lock mechanism for locking the shutter operating arm during the lifting operation of the disk lifting mechanism. The arm lock mechanism includes a lock rod which is provided for pivotal movement about a pivot shaft mounted on a lock base. The lock rod has a restricted angular range for pivotal motion and is biased by means of a spring. The arm lock mechanism becomes active when the cartridge holder approaches a position for initiating the operation of the disk lifting mechanism in order to shift the cartridge holder into the loading position, and to engage the lock rod to a lock rod receptacle which is cut-out of the shutter operating arm to prevent the latter from pivotally moving. Thus, the spring force of the return spring will not act on the disk cartridge held in the cartridge holder.
On the other hand, in the foregoing construction, since the shutter operating pin is provided on the cartridge holder and the arm lock mechanism is provided on the chassis, precise adjustment of the relative positions of the shutter operating pin and the arm lock mechanism becomes essential so that the arm lock mechanism is constantly effective. Excessive tolerance in the relative positions of the shutter operating pin and the arm lock mechanism may cause failure of the arm locking scheme, or in the alternative, incomplete shutter opening.
Furthermore, in the aforementioned construction, since the disk cartridge is not per se locked into the cartridge holder, it is still possible to withdraw the disk cartridge even after the arm lock mechanism locks the shutter operating arm. Therefore, if the disk cartridge is withdrawn immediately after the disk lifting mechanism starts, the movement of the disk cartridge causes damage to the disk and/or the magnetic head.